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Reactive molecular dynamics of the initial oxidation stages of Ni(111) in pure water: Effect of an applied electric field

Evidence and attribution

Authority of statements

Prose sections below (Summary, Methods, Findings, etc.) are curated summaries of the publication identified by doi, title, and pdf_path in the front matter above. They are not new primary claims by this wiki.

For definitive numerical values, reaction schemes, and interpretations, use the peer-reviewed article (and optional records under normalized/papers/ when present)—not this page alone.

Summary

The study applies ReaxFF MD to Ni(111) in contact with liquid water (~480 H₂O molecules, ρ ≈ 0.99 g/cm³, 300 K). The question is how an atomistic metal–water interface evolves under field-free versus strongly biased conditions relevant to corrosion and electrochemistry-inspired modeling. Without an external field, water does not dissociate, but the excerpt reports a charged double layer (positive Ni surface vs negative first water layer). With an imposed electric field (10–20 MV/cm), anodic oxidation proceeds: oxide growth is analyzed via anion ingress and Ni outward migration, with thickness scaling approximately linearly with field strength and faster corrosion at higher field, supporting a picture in which classical field magnitudes map to accelerated oxide propagation in these reactive simulations.

Methods

1 — MD application (atomistic dynamics)

Reactive molecular dynamics using ReaxFF investigates a Ni(111) surface in contact with liquid-like water at 300 K (normalized/extracts/2012assowe-venue-reactive-molecular_p1-2.txt).

  • Engine / code: ReaxFF MD (Abstract + Sec. 2 opening); N/A — MD engine/package not named on the indexed excerpt pages.
  • System size & composition: 480 H₂O molecules at ρ ≈ 0.99 g·cm⁻³ interacting with Ni(111) (Abstract, extract).
  • Boundaries / periodicity: N/A — explicit PBC / slab thickness details are not stated on the indexed excerpt pages.
  • Ensemble / timestep / duration / thermostat / barostat: N/A — NVT/NPT/NVE labels, timestep sizes, production run lengths, and thermostat/barostat algorithms are not stated on the indexed excerpt pages.
  • Temperature: 300 K (Abstract + Sec. 2 opening, extract).
  • Pressure / stress: N/A — not stated on the indexed excerpt pages.
  • Electric field: An external electric field between metal and solution is used for oxidation studies; the abstract reports intensities 10–20 MV/cm (note: the ACS PDF extract shows a likely typo “MeV/cm” on p. 1; interpret as MV/cm in line with standard electrochemical modeling units—verify pdf_path for the authors’ intended notation).
  • Replica / enhanced sampling: N/A — not stated on the indexed excerpt pages.

2 — Force-field training

N/A — application of an existing ReaxFF parameterization for Ni–water chemistry (Sec. 2 opening frames it as adopting the van Duin reactive FF approach, extract).

3 — Static QM / DFT-only

N/A — not the primary methodology on pp. 1–2 beyond contextual citations in the introduction (extract).

Findings

Outcomes and mechanisms (field-free): A water “bilayer” adsorbs on Ni(111) at 300 K; no water dissociation is observed without an applied field; surface Ni is charged positive and the first water layer negative, indicating an electric double layer (Abstract, extract).

Outcomes and mechanisms (with field): With an applied electric field, oxidation occurs; the abstract describes oxide film structural/morphological changes and interprets growth in terms of anion ingress into the metal and Ni outward migration toward the free surface (Abstract, extract).

Sensitivity and design levers: The abstract reports faster corrosion and approximately linear oxide thickness vs field intensity when increasing the field within the 10–20 MV/cm range studied (Abstract, extract).

Comparisons / limitations: The introduction discusses experimental challenges in observing earliest-stage oxidation and positions atomistic modeling as complementary; it also notes challenges in first-principles electrochemical potential control for long passive-film growth (Introduction, extract).

Corpus / KB honesty: Detailed trajectory lengths, thermostat algorithms, and quantitative oxide stoichiometry profiles are not on the pp. 1–2 extract—verify pdf_path for full results sections.

Limitations

  • Field magnitudes and simulation times are model-specific; quantitative comparison to experiment needs careful mapping of electrode potential to classical field protocols. The finite water slab and short production segments capture early oxidation trends more readily than long-time passive film evolution or pH-dependent ion adsorption that laboratory electrochemistry couples to oxide growth.

Relevance to group

Illustrates ReaxFF for aqueous metal oxidation and electrochemical interface modeling—adjacent to corrosion and battery interface themes.

Citations and evidence anchors

  • Abstract and introduction: Ni(111)–water setup, field strengths, double-layer and oxidation observations (J. Phys. Chem. A 2012, 116, 11796–11805; PDF pp. 1–2 per extract).

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